The invention relates to a method for variable manufacture of concrete railroad ties with or without prestressed reinforcement, for which molds are cleaned in a preparation station and provided with reinforcements, in order subsequently to be filled with concrete in a concreting and shaking station, and the railroad ties are cured by a heat treatment, and to an apparatus for carrying out this method.
Prestressed reinforced concrete railroad ties or non-prestressed reinforced railroad ties are manufactured worldwide by several methods. At the present time, especially four systems are used.
In the case of an immediate removal of formwork with a subsequent stressing process, the railroad ties are produced in a mold with holes, in which prestressing steel is subsequently inserted and stressed by means of nuts, that are left open in the molds by die plates. The railroad ties are cured in heating chambers, after the formwork is removed from the railroad ties and only concrete objects are placed into the heating chambers.
For the manufacture of prestressed concrete railroad ties with direct connection, there are several common methods, such as a late removal of formwork method using a long clamping bed, a late removal of formwork method using a short clamping bed in a circulating method, and a late removal of formwork in the circulating method. For the first two methods, long blocks of reinforced concrete railroad ties, which hang together, must be sawn apart. On the other hand, in the case of the late removal of formwork in the circulating method, the individual railroad ties are next to one another in multiple molds. In the case of the late removal of formwork method using the long clamping bed as well as using the short clamping bed, which can be realized only in large stationary plants because of the appreciable dimensions of the molds of between about 15 and 150 meters, curing creates difficulties, since it can be brought about only partly under sheets placed down or by means of a cumbersome transport of the very long molds into a heating chamber. For the late removal of the formwork in the circulating method, the multiple molds are transported into a heating chamber tunnel. This type of curing in heating chamber tunnels with a fixed passage cycle has the disadvantage that similar types of railroad ties with different curing times cannot meaningfully be manufactured in the same passage.
It is therefore an object of the invention to create a method and an apparatus for variable manufacture of concrete railroad ties with and without prestressed reinforcement, with which it is possible to produce different types of railroad ties, with or without prestressed reinforcement, in the same plant in the same production cycle.
Pursuant to the invention, this objective is accomplished by producing all railroad ties in multiple molds, preferably in quadruple molds having identical external dimensions, and carrying out heat treatment in heating chambers, which are loaded and unloaded with the concrete-filled molds by means of a shelf servicing device, which supplies the molds to a stress relieving and emptying station ahead of a preparation station.
Pursuant to the invention therefore, working with large molds in a short clamping bed or a long clamping bed is omitted. Instead, basically all concrete railroad ties are produced in multiple molds using individual molds, which are disposed next to one another and are intended to be put under tension individually. This has the additional advantage that alternately the reinforcement can be omitted in individual molds and even in individual molds within a multiple mold, so that, for example, reinforced railroad ties as well as railroad ties, which are not reinforced, can be produced within a multiple mold, such as a quadruple mold.
In a further development of the invention, the different concrete railroad ties are produced in multiple molds, which consist of a load-bearing frame and an exchangeably inserted inlay shaped plate This construction results in a standard dimension for the external frame, which enables the heating chambers to be subdivided in a standard fashion in a particularly advantageous manner to correspond to this frame size. This, in turn, permits very different railroad ties to be manufactured in a continuous method with different curing times and different temperatures in the heating chambers by means of a computer-controlled shelf servicing device. Moreover, retrofitting multiple molds for different concrete railroad ties is extremely simple, in that only the installed inlay shaped plate can be exchanged. In addition, the possibility also arises in this manner of being able to produce different concrete railroad ties simultaneously within a multiple mold.
For carrying out the method, a circulating production plant is used, for which a preparation station for empty molds is followed by a concreting and shaking station with a transfer transport segment to a shelf servicing device of a curing station, which has a plurality of heating chambers and is followed by an emptying station containing a stress-relieving station, and a buffer segment for the molds preferably being disposed downstream from each station.
The plant of the present invention can be designed as a mobile plant and have components and capacity adapted depending on requirements. The plant can be built in container units, which only have to be connected electrically and for which expensive crane equipment is not required, since the transport of the molds from and to the curing equipment can be designed very simply as a result of the convenient multiple molds used, which preferably should be quadruple molds.
By using a plurality of separated heating chamber segments, a mixed production of prestressed concrete railroad ties and non-stressed reinforced railroad ties is possible. It should be noted here that the prestressed concrete railroad ties require a longer curing time. The non-stressed reinforced railroad tie molds can therefore be used twice a day. The computer-controlled shelf servicing device places reinforced concrete railroad ties and non-stressed reinforced railroad ties separately in the heating chambers and transports the cured railroad ties, as desired, for removal of formwork. The total plant requires only little space in relation to conventional late formwork removing systems. At the same time, there is yet the advantage that the molds of the plant can also be used in other plants with different production methods.
The method and the apparatus of the present invention furthermore also have the advantage that accessories for solid tracks and wide railroad tie tracks, such as sound absorbers or filling stones, also can be produced therewith and, moreover, once again in the same continuous method, merely by using other molds. The differences between these accessories and prestressed concrete railroad ties or reinforced railroad ties, especially with respect to temperature and curing time, can be collected and taken into consideration appropriately fully automatically by means of the programmed shelf servicing device.
Further advantages, distinguishing features and details of the present invention arise out of the following description of an example by means of the accompanying drawing.